The characteristics of ciliary activity and the periciliary fluid layer of the lung are vital to the lung defense mechanism of mucociliary clearance. Because impaired mucus transport results in chronic obstructive lung disease, it is important to understand the underlying cellular regulatory mechanisms of mucociliary transport. In this proposal the basic electrophysiological characteristics of respiratory tract ciliated and non-ciliated cells from human (normal and cystic fibrosis) and rabbit trachea will be investigated to determine the involvement of membrane properties in the regulation to ciliary activity and the depth and composition of the periciliary fluid layer in the lung. We will measure membrane potential (Vm) and whole-cell currents from human and rabbit ciliated cells using whole-cell patch clamp techniques. Cells will be grown in culture conditions designed to maintain a differentiated cell type. The effects of B-adrenergic agents, cAMP analogs, prostaglandins, Ca++ ionophores and mechanical stimulation on the cell Vm and ion currents, especially C1- and K+, will be examined. With single-channel patch clamp techniques, we intend to identify and characterize the ion channels of isolated human and rabbit ciliated cells. Because C1-, K+ and amiloride-sensitive Na+ channels have been found in other RT cell preparations, we will determine whether these channel types are present in our identified cell types. Preliminary evidence implicates a role for Ca++ and stretch-activated channels in RT ciliated cell physiology, but their presence has not, as yet, been demonstrated. Consequently, we will determine if Ca++ and stretch-activated channels are also present in ciliated cells. The basic properties of the ion channels present will be determined. Regulation of ion channels by Ca++ and cAMP will be investigated. By understanding the cellular mechanisms that regulate late mucociliary activity, the conditions that cause a failure of mucus transport and predispose the lung to disease can be identified and improvements made in preventive and therapeutic pulmonary care.